Quantum dots (QDs) have the advantages of a tunable wavelength of emitted light, a narrow wavelength range of emitted light (15-30 nm), excellent light, thermal and chemical stability, and ease of being formed by a solution method, so that they have been widely applied to QDs light-emitting diodes, (QLEDs). QLEDs not only have the unique optoelectronic advantages of QDs, but also can be formed by the well-established approach of forming a film in organic light-emitting diodes (OLEDs) from a solution. In this regard, QLEDs are expected to be applied to a new generation of flat display and lighting with high color quality and low power consumption, and thus are drawing increasing attention from the skilled in the art.